Route climbing is a team sport. When you're climbing you can enjoy the simple task of pulling your way up the wall. When your partner is climbing, you have to keep him safe as possible until he's back on the ground. That's why it's smart to have a belay device with assisted braking technology when you're learning at the gym or even working complicated routes in caves and steep crags. Mammut's Smart 2. 0 Belay Package not only comes with an assisted braking belay device, but also a locking carabiner that the device was specifically designed for. The Smart 2. 0 Belay Device handles very similarly to most belay devices, with an exception to a clever design that automatically brakes the rope if ever pulled too suddenly. Although not foolproof, like any belay device, the Smart 2. 0's additional braking is still exceptionally comforting when you're belaying your buddy during the first lead test, or working critical slack management when your friend could possibly deck on a route. As for the Smart HMS Biner, well Mammut designed it specifically for the Smart 2. 0 Belay Device to promote easy handling from top to bottom. It features the standard screw lock with an additional safety gate that prevents cross-loading, which is a common nuisance unless you have a safety gate like this carabiner's. The Smart HMS also has a keylock nose to eliminate snagging when you're taking partners on and off belay.